Distribution and clinical significance of lupus anticoagulant and anticardiolipin antibody in 349 patients with systemic lupus erythematosus.

Samples from 349 patients with systemic lupus erythematosus (SLE) were tested simultaneously for lupus anticoagulant (LAC) and anticardiolipin antibodies (ACL). LAC was detected in 27.2% of 349 SLE patients by a modified mixing kaolin clotting time. ACL was detected in 34.7% by enzyme-linked immunosorbent assay. Only half of the patients who had LAC or ACL were positive for both of them. In addition, isotypes of ACL in these patients were studied. The IgG isotype was detected in 81.8% of 121 patients, and more than half had only the IgG isotype. When clinical features of patients with LAC or ACL were studied, the incidence of thrombosis, fetal loss, and thrombocytopenia were significantly higher in both groups compared with patients without LAC or ACL. In particular, the patients with both LAC and ACL showed the highest risk of fetal loss (89%) during pregnancy. These results indicate that LAC and ACL are detected in partly different groups of SLE patients, but both of these groups are clinically similar.